He was appointed a member of an ecclesiastical commission for reforming the church in 1787, in which capacity he was virtually minister of public worship. In 1791-1792 he became a leading member of the financial and general committees of the Riksdag. After the king's death Nordin shared in the general disgrace of the Gustavians and lived in retirement at the little town of Härnösand, where he held the post of lector at the gymnasium. But he reappeared prominently on the political scene during the Riksdag of 1800, and in 1805 was consecrated bishop of Härnösand. Though he lacked the brilliant qualities of his rival Wallqvist, Nordin had the same alertness and penetration, and was infinitely more stable and disinterested. One of the most learned men of his day, he devoted his spare time to history, and discovered that many of the oldest and most cherished Scandinavian manuscripts were clever forgeries. Like Jean Hardouin he got to believe that a great deal of what is called classical literature was compiled by anonymous authors at a much later date, and he used frequently to startle his colleagues, the Gustavian academicians, by his audacious paradoxes.
He left behind him a colossal collection of manuscripts, the so-called Nordinska Samlingarna, which were purchased and presented to Upsala university by Charles XIV of Sweden and form the groundwork of the well-known Scriptores rerum Suecicarum medii aevi. Nordin published during his lifetime Handlingar till uplysning af svenska krigs-historien (Stockholm, 1787-1788). His academical addresses came out at Stockholm in 1818 under the title Minnen ofver namnkunniga svenska män. His Dagbok or Diary did not appear till 1868.
See also: List of Swedish politicians